For photographers tasked with covering President Obama, U.S. Secret Service agents often accidentally slip into the shot from time to time. But in a series of images recently released, photojournalist Jacquelyn Martin of The Associated Press shifted her lens to capture some of the country's most mysterious men and women.

"In my time covering the White House the U.S. Secret Service and its visual alphabet of dark suits, sunglasses, and earpieces has fascinated me," Martin wrote on an AP Images Instagram post.

Secret Services agents serve in dangerous and high pressure jobs, responsible for protecting the life of the president of United States and other dignitaries. The agency has its own "intricate choreography," as Martin describes it, and agents work hard to remain vigilant against any and all threats.

Her curation of these stunning black and white photos allows us to see that choreography at work, and shines a spotlight on the quiet agents trying so hard to blend in.